In brief: Regulations concerning the testing of ring slings and wraps will be mandatory in January of 2018. Similar regulations have gone into effect for mei tais and SSCs; these do not affect ring slings, so yes, you can still send your wrap to be converted until January. This page explains what will happen as the regulatory deadline approaches.
What the standard says, in brief: all wraps and ring slings must be tested, both for strength and for the clarity of the directions. The testing is looking to make sure that the fabrics used are safe, and that the carrier can be used safely as it is designed. The standard specifies that testing must be redone whenever there is a "material change" in the design. This is currently interpreted to mean that, for example, if I make a WCRS out of a Didymos wrap, it may not perform the same as a WCRS made from a Girasol wrap (because the two wraps are from different manufacturers), and I would need to test both. It also means that once a wrap has been used, there's no way to know how the fabric will hold up in testing (because I have no way of knowing what happened to the wrap before it got to my hands -- whether it was exposed to smoke, or stored for years, or improperly washed, any of which could damage the weave and lead to a failure). Each testing cycle will cost between $400-800. It simply won't be possible for me to test a sling from every wrap manufacturer. In fact, I would need to sew a minimum of 25 slings from a given manufacturer just to break even on testing costs, and as a business owner, I need to take care of my bottom line and make sure I'm not just breaking even, but making a profit to provide for my family. All of these factors add up to my needing to drastically scale back the fabrics I offer in stock, and cease production of WCRS made from used wraps, and from those for whom it wouldn't be practical for me to do testing on. (This includes shoulder redos and other custom fabrics as well.)
I will be submitting my in-stock linen and French twill fabrics for testing. I will probably not be able to do all the organic fabrics (they're all different weaves and weights and will require separate tests for each one). I had hoped to work with retailers to test their biggest-selling WCRS fabrics, including standard and diamond-weave Girasols and perhaps one or two other brands, but cooperation has not yet materialized, so I can offer no guarantees on those brands. I will not be able to do conversions on anything I haven't tested, and anything used is also a no-go. This will mean that the sling market will change drastically, in that those one of a kind conversions will no longer be allowed, nor the legacy-wrap type conversions. I'm sure there will be unscrupulous (or unknowing) people who will continue to do them, but they will be in violation of federal laws, and I will not be among them. And no, sending your wrap to Canada will also not be a workaround, since any product sold into the US has to comply, so your Canadian converter can't legally send it back to you.
A note on abbreviations you might see -- I am a member of the BCIA, the Baby Carrier Industry Alliance. (Actually I was a founding board member, but now I'm just a regular member.) The BCIA is essentially an industry club. While there are BCIA members who volunteer to work with the CPSC (Consumer Product Safety Commission) on the ASTM (American Society of Testing and Materials, though now they just use ASTM because it's international) sling standard, the BCIA does not set or have other undue influence on the standard's creation. They help members reach compliance with the standards and the CPSIA (above), but there is no "BCIA certification" or "BCIA compliance". Either a business complies with the standards and rules or they don't; the BCIA doesn't judge that or certify its members. The phrase "BCIA Compliant" in a seller's listing is a huge red flag that they are probably not following the rules, since they either don't understand or are ignorant of what they actually need to do to comply.